The Cytobiology Core is designed to meet common needs of the projects within this proposed Program. The scope of the Cytobiology Core has expanded considerably compared with the Morphology Core of the existing Program Project. Two major additions have been made to the light and ultrastructural expertise provided by the Core. First, immunocytochemical localizations of the K(I) and BK(Ca) channel proteins and active versus inactive ODC and in situ hybridization of ODC mRNA will be conducted at the light and ultrastructural levels. Second, analytical techniques will be employed to quantitate tissue polyamines, polyamine-protein adducts, and isodipeptide bonds. All projects within the proposed Program will utilize one or more of these capabilities provided by the Cytobiology Core. Advantages of the Cytobiology Core will be consolidation of cytologic expertise, both technical and scientific, to avoid duplication of effort; cost containment and avoiding repetition of commonly used techniques; and added control over experiments because the same individuals will perform and interpret similar data for the projects. Improvements in the scope, scientific expertise, and usage of the Cytobiology Core make it a crucial focus for the Program Project.